John h



(N0 Model.)

J. H. J. SCHMIDT. Pneumatic Brake for Elevators, 8L0.

Patented Jan. 4,1881.

FITG-l.

Invent Or yw-w -LITHOGRAPHER. WASHINGTON D. C

:peculiar construction of these pinions is seen I V UNITED STATES PATENTJOHN J. SCHMIDT, OF CINCINNATI, OHIO, ASSIGNOR OF ONE-HALF TO FRANK X.OEHLER, OF SAME PLACE.

PNEUMATIC BRAKE FOR ELEVATORS, 80C.

SPECIFICATION formingpart of Letters Patent No. 236,184, dated January4, 1881.

Application filed July 22, 1880. (No model.)

To all whom it may concern:

Be itknown that I, JOHN H. J. SCHMIDT, of Cincinnati, Hamilton county,Ohio, have invented a new and useful Pneumatic Brake for Elevators, &c,of which the following is a specification. Y

My invention consists in applying a pneumatic brake either to the beamor frame or platform of a cage or carriage of I an elevator or otherhoisting apparatus, which brake is automatically brought into action forthe purpose of instantly arresting the descent of the cage the momentthe cable breaks, or when, from any other cause, a certain predetermineddescending speed is exceeded, the preferred construction of the brakebeing as follows:

A pump or other suitable compressor is attached to the car, and is setin motion during the descent of the latter, so as to force air into atank or receiver and maintain therein any desired pressure-say fortypounds to the square inch-which pressure having been obtained, said pumpis rendered inoperative for the time being. While the cage or carriageis making its usual trips this imprisoned air remains inactive, but themoment the cable breaks and the car begins to descend at a high velocitya governor or other regulator immediately opens a throttle-valve andallows the compressed air to rush into a cylinder and actuate a piston,which latter device brings into service the brake proper, ashereinaftermore fully described.

In the annexed drawings, Figure 1 is a plan of the under side of theplatform of an elevator car or cage provided with my pneumatic brake.Fig. 2 is an enlarged view of the brake proper. Fig. 3 is an elevationof the ratchet mechanism of the driving-shaft of the brake, and Fig. 4:is a modification of the invention. Referring to Fig. l, A representsthe platform of a stage or car of an elevator or other hoistingapparatus; andB B are the customary Vertical guides or stanchions of thesame, said guides being provided, respectively, with racks b b,wherewith are engaged pinionsc c, at the opposite ends of driving-shaftO. The

in Fig. 3, a reference to which illustration will show that the one o isloosely journaled on shaft 0 and carries a pawl, '01, that engages withthe teeth of ratchet-wheel D, which latter is firmly keyed to saidshaft. These ratchet-teeth should be set so as to insure the rotation ofwheel D and its attached shaft 0 only when the stage or car descends.

E E are housings inclosing the ratchet' wheels, and a a are thejournal-bearings for the shaft attached to said wheels.

Firmly secured at the mid-length of the driving-shaft O is a drum orpulley, F, surrounded with a brake-band, G, which band may consist of aflexible strap of steel or iron faced with rubber or leather or anyother material capable of increasing the friction between said drum andbrake. WVhen in its normal position the elasticity of band Gr maintainsit out of contactwith pulley F, as seen in Fig. 2. This band is coupledby a link, g, to the short arm of a lever, H, the longer arm of whichlever is attached to the rod i of a piston, I, which latter traversescylinder J. The head of this cylinder, through which passes the rod "i,is perforated at j to prevent air being imprisoned between said head andpiston I. while the other head is closed and has attached to it a pipe,K, leading to the tank or airreservoir L. which valve or cock is openedand closed by a governor or other suitable regulator, M, said It isthrottle-valve of this pipe,

regulator being driven from shaft 0 by means of gearing m, or otherwise.

N represents an air pump or compressor, the piston-rod n of thesamebeing driven from shaft 0 in any convenient manner, but, preferably,by means of an eccentric, O, riding loosely on said shaft and adapted tobe set in motion as soon as aclutch, P, is engaged with said eccentric.This coupling of the clutch and eccentric may be effected with a spring,R, interposed between said clutch, and an adj ustable collar, 1, or bymeans of a weight attached to a counter-arm of bell-crank S, asindicated by dotted lines, one end of said crank being forked andengaged with the clutch, while the other endof the crank has applied toit the rod of a piston, T, traversing a small cylinder, t, thatcommunicates with the air-reservoir L. U is a pipe that conducts thecompressed air from pump N into said tank or reservoir.

The operation of this preferred form of my pneumatic brake is asfollows: The governor M is first adjusted so as to keep thethrottlevalve is closed while the carriage A is traveling at itsordinary or safe speed, and the 10 spring R is set so as to cause theclutch 1 to engage with the eccentric until a certain desired pressureof air has accumulated within the tank L-say forty pounds to the squareinch. Theseprecautionshavingbcen observed, 1 5 the elevatororhoisting-machine is started; but during its ascent no rotation of shaft0 is effected on account of the peculiar arrangement of ratchet-wheelsD, previously described. As soon, however,-as the staging or car beginsto descend said shaft is set in motion, thereby actuating thecompressing device N, and thus forcing air into the tank or receptacleL. This act of compression is repeated at every descent of the car untilthe desired pressure has been obtained, at which moment piston Tisforced from its seat in cylinder 2, thus swinging the belLcrank S on itspivot, so as to disengage the clutch 1? from eccentric O, and render thepump N inoperative for the time being; but it air should leak from thereservoir L spring R will cause the clutch P to re-engage with eccentricO, and again pump up the required pressure.

It will thus be seen that a supply of compressed air is constantly andautomatically maintained in the reservoir, which air is utilized inoperating the brake in the following manner:

Immediately on the severance of the hoisting cable or chain it isevident the car will begin to descend very rapidly, but the moment itdoes the high velocity thereby imparted to the governor M will cause thelatter to open throttle-valve k, and allow the com- 5 pressed air tohave access to the cylinder J,

and drive its piston I toward the perforated headj of said cylinder.This forward stroke of the piston swings the lever H 011 its pivot anddraws the brake-band G so tightly around the drum F as to effectuallypret'ent further rotation of shaft 0, and, consequently, the car isinstantly locked in position and its further descent is at oncearrested.

From this description it will be seen that my pneumatic brake is whollyautomatic in all of its operations, and, therefore, it requires noattention from the person running the elevator.

In the modification seen in Fig. 4 the invention is shown as applied tothose elevators the guides of which are armed with ratchetbars,wherewith are engaged pawls or detents carried by the main beam of thestaging or platform. In this illustration the main beam A of the staginghas fitted in it a cylinder,

J, traversed by a piston, 1, that carries a tapering plunger, V, seatedin the stirrup W,

to which latter the hoisting-cable is attached in the usual manner. XXare inclined planes at the inner end of the rods that carry the 0 pawlsor detents Y. K is the pipe that conducts the compressed air intocylinder J, said pipe being carried down through the platform, where itcommunicates with a reservoir similar to the one L. In this modificationno governor or regulator is employed; but care must be taken to allow asufficient volume of compressed air in the cylinder J to balance theweight of the hoisting rope or chain. Immediately after the breakage ofthis rope the compressed air is allowed to flow into said cylinder anddepress its piston l, which act forces the wedge-plungerVdown betweenthe two inclined planes X X, thereby compelling their respective pawlsto engage with the 8 ratchets ofthe stanchions that confine the cage ina vertical path.

The invention may be further modified by employing a rotary compressorinstead of the reciprocating one, N, which rotary device may either beapplied directly on the shaft 0, or it may be geared or clutchedthereto.

As the brake is brought into service only after a certain predetermineddescending speed is exceeded, it is evident the action of the apparatusneed not depend on the breakage of a hoisting cable or chain; but it isto this class of elevators my invention is more especially adapted. Itmay, however, be as readily applied to those platforms or stagesattached directly to a piston or ram working water tight within acylinder, so as to prevent the descent of said piston in case it shouldexceed a predetermined speed caused by the bursting of the cylinder orof any of its waterconnections.

In Fig. l the various operative parts are shown as situated in the sameplane; but it is evident this arrangement may be varied withoutdeparting from the leading feature of my invention; and the right isreserved of changing the position of the brake or of entirelyreorganizing the apparatus to suit the special construction or locationof the elevator or hoister.

I claim as my invention- 1. In combination with a pneumaticelevator-brake, the driving-shaft O, air-compressor N, eccentric O,shiftable clutch P, lever S, piston T, cylinder t, spring R, and re- :20ceiver L, which receiver communicates with said cylinder t for thepurpose of permitting the compressed air to operate the piston T, asherein described.

2. In combination with the air-cylinder J, 125 pipe K, and tank L of apneumatic brake for elevators, the throttle-valve 7c and regulator M,for the purpose described.

3. In combination with shaft 0, gearing with the racks b b of anelevator, the air-cyl- 130 IIO inder J, lever H, brake-band G, and drumF, In testimony'of which invention I hereunto which drum is attached tosaid shaft, as herein set my hand. explained- JOHN H J SCHMIDT 4. Thecombination ofdriving-shaft O, brake 5 apparatus F G H I J regulator isM.,reservoir Witnesses:

L, and compressing devices N O P R S T 1?, JAMES H. LAYMAN,

substantially as described. JEREMIAH F. TWOHIG.

